Survey basemaps calibration and georeferencing (Raster images module)
TeleCAD-GIS includes a subsystem for processing, digitizing and storing the survey raster image plans. At the same time it inherits AutoCAD's tools for work with raster images in general.
Algorithms (tools) for removal of the distortions that occur during the scanning process of paper documentation or distortions that are consequence of storing conditions of such documentation (e.g. high humidity level) are provided. Elimination of deformations is performed according to the required standards.
Such processed data forms the basis for planning, designing, and compliance of:
• site plan (recorded by GPS device) with planned (survey plans),
• outdated geodetic plans with the factual situation (e.g. orthophoto images),
• vector representation of planned structures with existing structures on the ground.
Fully automated positioning of the scanned content in to the country's coordinate system and connection of scanned sheets into the continuous map is provided. Information about the position (coordinates) of processed raster base maps is stored either in the separate DWG file, or in a corporate database of map material.
Calibration (elimination of deformations)
It is not enough to simply scan the geodesic plan in order for it to become a reference layer. When translating the map from analog to digital format the program ensures that after conversion geodesic plans keep their basic properties:
• spatial determination,
• geometry and mathematical accuracy,
• and content integrity.
Accuracy required by law and calibration quality control using the statistic test of blunder is provided.
Storage and usage
Raster module provides indexed storing of processed raster base maps to a hard disk or a database of cartographic material, thus preventing the design using outdated or unmapped layers. Simultaneous multi-user access to a database that contains unified set of indexed geodetic plans and maps is enabled. Such maps can easily be loaded to the active drawing (to the area covered by the active screen, i.e. to the area of user's current attention).
Format conversion (among other) includes:
• loading of scanned plans or maps in image formats: TIFF, JPEG, BMP and GIF,
• automatic conversion of raster image into transparent AutoCAD display,
• especially optimized algorithms for linearization during the conversion of 16 or 24 bit color base maps to their bitonal (one bit) state, i.e. black and white.